UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS. 


COLLEGE  OF  AGRICULTURE. 


AGRICULTURAL  EXPERIMENT  STATION. 


CALIFORNIA 


OLIVE  OIL; 


ITS  MANUFACTURE. 


ByG.  W.  SHAW. 


Olive-crusher  at  Camulos;  first 
built  in  the  State,  aside  from  the 
one  at  San  Diego  Mission. 


BULLETIN   No.   158 

(Berkeley,  Cal.,  June,  1904.) 


W.    W.    SHANNON. 


SACRAMENTO: 

:    :    :    superintendent  state  printing. 
1904. 


BENJAMIN  IDE  WHEELER,  Ph.D.,  LL.D.,  President  of  the  University. 

EXPERIMENT  STATION  STAFF. 

E.  W.  HILGARD,  Ph.D.,  LL.D.,  Director  and  Chemist. 

E.  J.  WICKSON,  M.A.,  Horticulturist. 

W.  A.  SETCHELL,  Ph.D.,  Botanist. 

ELWOOD  MEAD,  M.S..  C.E.,  Irrigation  Engineer. 

C.  W.  WOOD  WORTH,  M.S.,  Entomologist. 

R.  H.  LOUGHRIDGE,  Ph.D.,  Agricultural  Geologist  and  Soil  Physicist.    {Soils  and  Alkali.) 

M.  E.  JAFFA,  M.S.,  Assistant  Chemist.    (Foods,  Nutrition.) 

G.  W.  SHAW,  M.A.,  Ph.D.,  Assistant  Chemist.    (Starches,  Oils,  Beet-Sugar.) 

GEORGE  E.  COLBY,  M.S.,  Assistant  Chemist.    (Fruits,  Waters,  Insecticides.) 

RALPH  E.  SMITH,  B.S.,  Plant  Pathologist. 

A.  R.  WARD,  B.S.A.,  D.V.M.,  Veterinarian,  Bacteriologist. 

E.  H.  TWIGHT,  B.Sc,  Diploma  E.A.M.,  Viticulturist. 

E.  W.  MAJOR,  B.Agr.,  Animal  Industry. 

A.  V.  STUBENRAUCH,  M.S.,  Assistant  Horticulturist,  in  charge  of  Substations. 

WARREN  T.  CLARKE,  B.S.,  Assistant  Field  Entomologist. 

H.  M.  HALL,  M.S.,  Assistant  Botanist. 

H.  J.  QUAYLE,  A.B.,  Assistant  Entomologist. 

GEORGE  ROBERTS,  M.S.,  Assistant  Chemist,  in  charge  Fertilizer  Control. 

C.  M.  HARING,  D.V.M.,  Assistant  Veterinarian  and  Bacteriologist. 

C.  A.  TRIEBEL,  Ph.G.,  Assistant  m  Agricultural  Laboratory. 

C.  A.  COLMORE,  B.S.,  Clerk  to  the  Director. 


EMIL  KELLNER,  Foreman  of  Central  Station  Grounds. 

JOHN  TUOHY,  Patron,  ) 

>  Tulare  Substation,  Tulare. 
JULIUS  FORRER,  Foreman,  ) 

J.  E.  McCOMAS,  Patron,  Pomona, 

J.  W.  MILLS,  Superintendent,  Ontario,  )■  Southern  California  Substation. 

JOHN  H.  BARBER,  Assistant  Superintendent,  Ontario, 

A.  A.  KNOWLTON,  Patron, 

J.  H.  OOLEY,  Workman  in  charge, 

ROY  JONES,  Patron,        ) 

V   University  Forestry  Station,  Santa  Monica. 
WM.  SHUTT,  Foreman,    \ 

H.  O.  WOODWORTH,  M.S.,  Foreman  of  Poultry  Station,  Petaluma. 


y  University  Forestry  Station,  Chico. 


The  Station  publications  (Reports  and  Bulletins),  so  long  as  avail- 
able, will  be  sent  to  any  citizen  of  the  State  on  application. 


CALIFORNIA  OLIVE  OIL, 


Although  this  Station  has  issued  several  publications*  from  time  to 
time,  both  in  the  form  of  bulletins  and  of  special  articles  in  the  Annual 
Reports,  treating  of  various  phases  of  the  olive  industry,  yet  the 
increasing  number  of  inquiries  as  to  the  making  of  oil  upon  a  com- 
mercial scale  makes  it  evident  that  the  brief  discussion  given  in  the 
bulletins  issued,  and  the  scattered  condition  of  .the  other  literature  deal- 
ing with  the  subject  (some  of  it  having  been  destroyed  by  fire),  render  a 
more  detailed  discussion  of  the  matter  desirable  at  this  time.  This  is 
the  more  necessary  since  the  changed  commercial  conditions  have  made 
it  almost  imperative  that,  with  few  exceptions,  the  manufacture  of 
olive  oil,  as  with  dairy  products,  be  conducted  by  central  plants  on  a 
considerable  scale,  rather  than  by  numerous  small  outfits  connected 
with  the  orchards  themselves.  This  mill  may  be  either  cooperative,  as 
with  many  successful  creameries,  or  under  private  ownership,  but, 
above  all,  the  conditions  surrounding  its  location  and  operation  must 
be  of  the  best,  and  the  equipment  of  the  mill  must  be  of  the  highest 
efficiency.  As  the  making  of  butter  on  the  farm  has  rapidly  given 
way  to  creamery  methods,  so  the  making  of  olive  oil  in  a  small  way 
must  surely  give  way  to  larger,  centralized  mills. 

By  thus  centralizing  the  manufacture  the  operations  of  making  and 
marketing  the  product  can  be  better  systematized,  more  skilled  labor 
generally  employed  in  the  mill,  and  the  large  number  of  very  indiffer- 
ent brands,  which  in  many  cases  are  even  inferior  to  its  neutral  oil 
competitors,  cottonseed  and  peanut,  can  be  materially  lessened.  As  a 
result,  especially  if  the  industry  be  coupled  with  that  of  pickling,  its 
natural  complement,  the  manufacturer,  on  account  of  the  larger  output 
and  the  possibility  of  handling  at  a  greater  profit  his  highest  grade  of 
olives  in  the  form  of  pickles,  can  afford  to  pay  the  grower  a  price  for 
olives  which  will  return  a  fair  profit — a  condition  which  can  not  be 

*  Notes  on  California  Olives.     Bulletin  92.     By  E.  W.  Hilgard. 

Investigations  of  California  Olives  and  Olive  Oils.     Bulletin  104.     By  E.  W.  Hilgard. 

Olives:    Pickling  Processes;   Notes    on    Varieties,   Oil    Machinery,   etc.     Report  of 

Experiment  Station,  1894-95.     By  A.  P.  Hayne.  t 

Olives  and  Olive  Oil.     Report  of  Experiment  Station,  1895-97.     By  A.  P.  Hayne. 
Analyses  of  California  Olives.     Report  of  Experiment  Station,  1895-97,  page  193.     By 

G.  E.  Colby. 
Olives.    Bulletin  123.     By  F.  T.  Bioletti  and  G.  E.  Colby. 
Report  on  the  Condition  of  Olive  Culture.     Bulletin  129.     By  A.  P.  Hayne. 
Pickling  Ripe  and  Green  Olives.     Bulletin  137.     By  F.  T.  Bioletti. 


4  UNIVERSITY    OF   CALIFORNIA — EXPERIMENT   STATION. 

said  to  obtain  generally  where  either  of  these  industries  is  conducted  on 
a  very  small  scale  on  the  orchard  itself. 

The  improvement  in  the  conditions  surrounding  the  dairy  industry 
since  the  establishment  of  central  creameries  in  place  of  the  individual 
churn  on  the  farm  is  a  standing  example  of  the  advantages  to  be  gained 
by  central  plants  both  from  the  standpoint  of  the  producer  of  the  raw 
material  and  the  manufactured  product.  The  growing  of  the  olive  is  a 
branch  as  distinct  from  the  making  of  oil  as  the  production  of  milk 
from  the  making  of  butter. 

Under  the  present  condition  there  is  a  wide  range  in  the  class  of 
equipments  used  in  the  making  of  olive  oil,  ranging  all  the  way  from 
the  most  crude  machines  operated  entirely  by  hand  in  a  very  haphazard 
manner,  to  the  modern  mill  operated  by  power  and  equipped  with  the 
latest  mechanical  appliances  for  handling  both  the  raw  material  and 
the  finished  product. 

After  a  very  careful  study  of  the  conditions  which  obtain  in  the 
manufacture  of  olive  oil  today,  the  writer  can  not  recommend  in  any 
way  the  attempt  to  handle  olives  for  oil  on  a  small  scale  in  connection 
with  the  orchard,  where  the  idea  is  to  make  oil  in  a  commercial  way. 
In  a  small  way,  of  course,  for  home  use,  hand  work  with  a  small  plant 
can  be  utilized,  but  if  it  is  hoped  to  manufacture  oil  at  a  profit  com- 
mensurate with  the  care  and  labor  expended,  automatic  machinery  to 
reduce  the  cost  and  facilitate  the  handling  of  the  goods  so  far  as 
possible,  and  the  most  economical  arrangement  of  the  machinery  in  the 
building,  to  prevent  so  far  as  possible  all  doubling  back  on  the  work, 
should  be  employed. 

It  is  true  that  certain  makers,  operating  on  a  small  scale  and  with 
hand  apparatus,  have  made  a  success  by  establishing  a  limited  clientage 
for  their  particular  brand  of  oil,  made  of  the  highest  quality;  but  the 
record  of  successes  in  this  way  is  very  small,  and  it  must  be  said  that 
those  who  entered  into  the  business  in  a  small  way  have  become  dis- 
couraged for  one  reason  or  another,  and  in  some  cases  have  entirely 
abandoned  the  making  of  oil. 

In  some  cases  this  has  been  hastened  from  the  fact  that  in  the  early 
stages  of  olive  planting  many  varieties  of  olives  were  planted  which 
were  not  well  adapted  to  pickling  on  account  of  their  inferior  size  and 
appearance,  nor  were  they  well  adapted  to  oil-making  on  account  of 
either  the  quality  or  the  quantity  of  oil  furnished.  Another  factor 
which  has  some  bearing  upon  this  condition  has  been  the  planting  of 
fruit  upon  the  poorest  kind  of  soil,  and  the  general  lack  of  care  given 
to  the  orchard  after  planting,  under  the  mistaken  idea  that  the  olive 
tree  would  grow  under  the  most  unfavorable  horticultural  conditions. 
Indeed,  this  idea  was  fostered  and  encouraged  by  writers  with  facile 
pens  in  the  earlier  years  of  the  industry.     As  a  result  of  these  teach- 


CALIFORNIA    OLIVE    OIL.  5 

ings  large  areas  were  planted  under  such  unfavorable  conditions  that 
almost  without  exception  they  have  given  such  poor  returns  as  to  dis- 
courage both  the  grower  and  his  neighbors.  The  effect  of  errors  of  this 
kind  is  difficult  to  overcome.  Such  a  condition,  however,  is  not  confined 
to  this  industry,  but  is  to  be  seen  in  the  early  stages  of  all  horticultural 
crops.  As  an  offset,  however,  it  should  be  distinctly  understood  that 
where  the  olive  orchard  has  been  planted  upon  soil  well  adapted  in 
depth,  quality,  and  physical  condition,  and  the  varieties  planted  have 
been  those  good  for  pickling  and  oil,  and  the  orchard  has  been  well  cared 
for,  favorable  results  have  been  secured,  and  are  still  being  secured,  and 
the  orchard  has  returned  a  reasonable  profit  on  the  investment.  It 
can  not  be  insisted  upon  too  strenuously  that  the  olive,  like  other  fruit- 
bearing  trees,  appreciates  a  good  soil  and  requires  care,  and  under  no 
other  conditions  can  favorable  returns  be  expected  from  it. 

It  is  not  the  object  of  this  bulletin  to  discuss  the  horticultural  features 
of  the  olive  crop,  further  than  to  call  attention  to  some  of  the  causes 
which  have  tended  to  bring  the  olive  crop  into  disrepute,  and  to  call 
the  attention  of  the  readers  of  this  bulletin  to  a  discussion  of  the 
cultural  conditions  for  the  olive  as  set  forth  in  Bulletin  No.  129  of  this 
Station. 

Another  serious  obstacle  to  the  success  of  the  industry  has  been 
the  indifferent  quality  of  oil  which  has  been  made  by  so  many 
operators.  In  the  face  of  the  competition  of  so  cheap  an  oil  as  the 
cottonseed,  the  chief  competitor  of  the  olive  as  an  edible  oil  producer, 
and  the  attendant  high  cost  of  producing  strictly  pure  high-grade  olive 
oil,  unless  the  maker  is  prepared  with  the  most  efficient  machines  and 
so  handles  the  olives  as  to  turn  out  a  strictly  high-grade  product,  there 
is  little  inducement  to  enter  upon  the  making  of  olive  oil.  That  there 
should  and  would  be  a  ready  market  in  this  country  for  all  the  olive 
oil  which  could  be  made  in  this  State  is  evidenced  by  the  importations 
of  foreign  oil  as  set  forth  below. 

Imports  of  Olive  Oil. 

1902 

Spain $341,442  79 

France ...  940,318  42 

Italy 1,041,277  61 

Greece  and  Turkey 10,974  90 

Portugal -__  646  92 

Austria 449  16 

Total $2,335,109  80 

Total  for  nine  months  ending  March  31,  1903 1,314,676  00 

California  production 150,000  00 

To  make  this  oil,  however,  at  a  cost  which  will  compete  with  the 
foreign  product,  it  is  essential  that  only  the  most  efficient  machines  be 
employed  in  the  mills,  and  that  these  mills  be  of  such  capacity  as  to 
handle  large  quantities  of  olives  in  the  most  economical  manner.     This 


6  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION. 

can  only  be  done  by  central  mills  located  in  regions  best  adapted  in 
climate  and  soil  to  the  growth  of  the  olive.  Under  such  conditions  we 
may  reasonably  expect  the  oil  industry,  when  coupled  with  pickling,  to 
give  reasonable  returns  upon  the  investment.  As  with  the  dairy  industry 
it  is  only  under  such  conditions  that  we  can  expect  a  uniform  product 
to  be  made  at  the  lowest  possible  cost,  and  that  the  highest  price  can 
be  realized  for  the  fruit. 

There  is  a  market  demand  for  a  high-grade,  untainted  oil,  and  it  will 
not  tolerate,  at  a  price  which  will  repay  the  cost  of  making,  anything 
less  than  this.  Its  preference  will  rather  be  given  to  the  lower-priced 
neutral  edible  oils  appearing  under  the  undistinctive  name  "  Salad  Oil." 
There  are  those  who  at  first  put  up  good  products,  and  who  know  what 
a  good  product  is  when  they  taste  such  goods,  but  who  have  gone  out 
of  the  oil  business  simply  because,  in  spite  of  the  finest  kind  of  olive 
varieties,  machinery  and  installation,  they  neglected  the  most  element- 
ary precautions  and  spoiled  otherwise  perfect  raw  material.  At  first 
they  sold  all  the  oil  they  could  produce,  but  gradually  drifted  into 
careless  methods,  and  in  the  same  degree  accustomed  themselves  to  the 
foreign  tastes  in  their  oil  that  the  market  would  not  tolerate.  The 
market  is  invariably  blamed,  but  in  this  case  it  is  not  the  guilty  party; 
as  in  the  case  of  wine,  each  producer  is  firmly  convinced  that  what  he 
produces  is  perfection  itself,  and  if  the  market  does  not  appreciate  it,  it 
is  due  to  its  depravity.  Others  there  are,  who  failing  to  sell  a  spoiled 
article,  blame  the  variety,  soil,  climate,  and  everything  imaginable 
except  their  own  carelessness. 

Notwithstanding  all  that  has  been  said  there  are  many  in  the  State 
who  have  made  a  success  of  the  olive  business,  especially  those  who 
have  limited  themselves  to  the  growing  of  olives  and  selling  them  to  a 
mill  prepared  to  handle  the  crop  from  a  manufacturing  standpoint,  which 
under  such  conditions  could  afford  to  pay  a  fair  price  for  the  olives. 
The  cost  of  oil  machinery,  the  extreme  care  necessary  to  make  a  strictly 
high-grade  product  of  either  oil  or  pickles,  and  the  necessity  of  creating 
a  market,  should  deter  those  with  small  capital  from  going  into  the 
business  with  the  idea  of  making  oil  alone  for  profit. 

Location  of  the  Mill.— It  is  presumed  that  parties  contemplating  the 
establishment  of  a  mill  will  duly  consider  the  suiting  of  capacity  of  mill 
to  the  supply  of  raw  material  that  can  be  obtained  at  an  equitable 
price  and  within  easy  distance.  It  must  always  be  kept  in  mind  that 
everything  which  can  reduce  the  cost  of  handling  and  manufacture, 
so  long  as  it  does  not  reduce  the  quality  of  the  product,  counts  for 
success,  and  a  poor  location  of  the  mill  either  with  respect  to  handling 
the  crop  or  marketing  tin;  product  may  be  the  very  thing  which 
militates  against  success.     The  grower  must  realize  a  fair  profit  upon 


CALIFORNIA    OLIVE   OIL.  / 

his  olives  or  the  supply  of  raw  material  will  gradually  dwindle.  It 
is  probable  that  under  ordinary  conditions  of  crop  the  grower  must 
realize  not  less  than  $20  per  ton  for  the  olives  over  and  above  the  cost 
of  picking,  which  may  generally  be  considered  as  ranging  from  $8  to  $10 
per  ton.  At  present  the  ruling  price  for  olives  is  from  $25  to  $45  per 
ton,  depending  largely  upon  quality  and  variety.  Strictly  first-class 
pickling  olives  even  bring  as  high  as  $65  per  ton.  Since  the  recovery  in 
oil-making  does  not  exceed  about  50  per  cent  of  the  oil  in  the  olives? 
under  these  prices  the  oil  in  the  raw  state  will  cost  from  $1  to  $1.25  per 
gallon.  It  is  to  be  understood  that  the  higher  price  is  that  offered  for 
pickling  olives  without  grading,  and  that  these  are  graded  after  pur- 
chase; thus  the  oil  olives  resulting  from  the  grading  of  the  pickling 
olives  are  purchased  at  a  relatively  high  price,  probably  under  these 
conditions  sufficient  to  bring  the  price  up  to  $40  per  ton,  where  $30  is 
the  ruling  price  for  exclusively  oil  olives. 

The  location  having  been  considered  with  reference  to  olive  supply 
and  transportation,  attention  should  be  directed  to  the  water  supply, 
especially  if  pickling  is  to  be  coupled  with  oil-making;  and  this  must 
be  recommended  as  the  only  feasible  method  in  this  industry.  Only 
the  purest  water  should  be  used  in  the  preparation  of  olive  prod- 
ucts. The  water  should  be  free  from  excessive  quantities  of  mineral 
salts  and  should  especially  be  free  from  organic  contamination  and 
odors  of  all  kinds.  The  supply  should  be  bountiful  and  should  be 
introduced  into  the  building  through  large  pipes  tapped  at  several 
places  convenient  for  work.  The  main  pipe  should  be  of  sufficient  size 
and  the  pressure  adequate  to  permit  the  water  to  be  drawn  simulta- 
neously at  several  different  points  without  materially  interfering  with 
the  flow  at  any  one. 

CONSTRUCTION    AND    EQUIPMENT. 

The  Building. — This  need  not  be  large,  yet  should  be  sufficiently 
roomy  to  allow  ease  and  facility  in  work.  Inasmuch  as  the  presses  and 
mill  are  of  considerable  weight  the  building  should  be  solidly  con- 
structed where  the  weight  of  these  machines  is  to  be  supported,  and  if 
the  location  is  such  that  there  can  be  a  ground  floor  and  basement  the 
mill  is  best  placed  upon  the  ground  floor,  using  the  upper  part  of  the 
building  for  the  crusher,  the  ground  floor  for  the  grinding,  and  the  base- 
ment for  storage  and  bottling.  The  upper  floor  need  extend  over  only 
a  portion  of  the  building,  or  be  only  a  partial  floor,  upon  which  would 
stand  the  crusher  only,  where  the  operation  is  to  be  conducted  upon  a 
more  limited  scale.  According  to  capacity  of  the  mill  and  pickle  works 
and  its  location,  the  building  may  be  estimated  to  cost  in  the  neigh- 
borhood of  $1,000  to  $3,000. 

By  centralizing  the  work  more  labor-saving  machinery  can  be  em- 


8 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION. 


ployed,  as  has  already  been  found  quite  feasible  in  some  mills  in  the 
State,  notwithstanding  the  somewhat  widespread  idea  that  the  oil  is 
seriously  injured  by  such  an  innovation.  The  only  thing  needful  under 
these  conditions  is  to  have  the  arrangements  as  simple  and  easy  of 
cleaning  as  possible,  and  to  exercise  the  same  degree  of  cleanliness  and 
care  as  is  exercised  in  a  modern  creamery,  for  without  such  care  and 
cleanliness  it  will  be  found  impossible  to  make  an  olive  oil  which  will 
stand  the  test  of  trade. 

A  general  idea  as  to  several  arrangements  which  have  proven  and 
are  likely  to  prove  successful  and  convenient  may  be  had  from  several 
of  the  illustrations  which  appear  herein,  especially  that  shown  in  Figs. 
2  and  14.     The  subjoined  line  drawings,  showing  elevation  and  floor 


Fro.  1.    The  largest  olive-oil  mill  in  California. 


plans,  are  also  commended  as  very  convenient  arrangements,    where 
labor-saving  devices  are  to  be  introduced. 

Arrangement  of  Machinery. — The  arrangement  of  the  machinery  in 
the  factory  is  a  matter  of  extreme  importance  in  the  way  of  economy  of 
labor,  and  the  larger  the  capacity  of  the  mill  the  more  important  does 
this  factor  become.  A  certain  prominent  mill  in  this  State  employed 
during  one  season  thirty-three  men  working  twenty-four  hours  per  day 
(two  shifts)  for  the  making  of  about  five  hundred  gallons  of  oil.  By 
the  introduction  of  more  modern  machinery  and  adopting  a  more  sys- 
tematic arrangement,  the  management  was  able  to  reduce  the  number 
of  men  to  eleven  and  the  hours  to  twelve  for  the  same  amount  of  oil — 
a  material  saving  which  should  go  toward  the  profit  in  manufacture. 
Many  mills  are  still  so  inconveniently  arranged  as  to  require  a  large 
amount  of  hand  labor  in  shoveling  and  carrying  the  olives.     By  the 


CALIFORNIA    OLIVE    OIL. 


1 

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10 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 


Fig. 


Blowers,  crushers,  and  elevator:: 


introduction  of  link  belt  ele- 
vators and  carriers,  practi- 
cally all  of  tins  hand  work  in 
transferring  olives  and  pulp 
can  be  done  away  with,  and 
by  a  proper  arrangement  of 
tanks  and  the  introduction  of 
pumps  much  of  the  hand 
labor  in  transferring  the  oil 
can  also  be  saved. 

A  very  practical  and  mod- 
ern arrangement  of  trash- 
blower,  elevator,  crusher,  and 
elevator  leading  to  the  first 
press  is  shown  in  the  suit- 
joined  illustration  (Fig.  8). 

PRELIMINARY    OPERATIONS. 

Picking  the  Fruit.  —  The 
making  of  olive  oil  really 
begins  with  the  gathering  of 

the  fruit.     Whether  olives  are  to  be  used  for  pickling  or  for  oil-making, 

it    is    very    important    that  they   should  be  picked   carefully,   at    the 

right  time.     The    largest  quantity 

of    oil    possible   from  the  olives  is 

obtained  from   the  ripe  fruit,    but 

the  very  highest  grade  is  obtained 

from  the  fruit  picked  while  it  is  still 

hard,  but  sufficiently  ripe  to  allow 

the  pit  to  be  squeezed  out  without 

carrying     away    any  of   the    flesh 

with  it, 

One  can  not  be  wholly  governed 

by  color  to    determine  the  proper 

time  of  picking,  for  in  some  cases 

the  olives  may  become  quite  dark 

before    the     proper     condition     is 

reached,  but  again  the   fruit    may 

still  be  quite  green  in  color. 

For  whatever  purpose  the  olives 

are  to  be  used  they  must  be  gathered 

by  hand.     Raking  or  whipping  the 

t  n-<-    should    never   be  allowed,  not 

only  for  the  sake  of   preserving  the       Fi<;.  i.    olive  pickers,  with  lined  buckets. 


CALIFORNIA    OLIVE    OIL. 


11 


fruit  buds  on  the  trees,  but  also  on  account  of  the  bruising  of  the  fruit 
and  the  consequent  liability  to  fermentations  being  set  up  before  the 
olives  can  be  worked.  The  bruising  of  the  fruit  opens  the  way  for  the 
growth  of  fungi  which  ruin  the  good  qualities  of  the  oil,  and  every 
precaution  must  be  taken  to  prevent  such  bruising.  The  olives  must 
under  no  circumstances  be  poured  from  any  distance  onto  a  hard 
surface.  One  of  the  most  convenient  receptacles  for  the  use  of  pickers 
is  a  padded  bucket  as  shown  in  Fig.  4,  the  tops  of  trees  being  reached 
by  means  of  the  Titus  ladder  (Fig.  5). 

Nothing  is  more  conducive  to  systematic  and  economical  handling  of 
the  fruit  than  a  well-arranged  place  for  receiving  and  weighing  the  fruit 


Fig.  5.    Gathering  olives,  showing  the  use  of  the  ''Titus"  extension  ladder  on  wheels. 

as  delivered.  A  well-devised  systematic  record  of  the  fruit  received  is 
conducive  to  a  perfect  understanding  between  the  grower  and  the  packer 
or  mill,  as  the  case  may  be. 


Grading. — The  grading  of  the  olives  should  be  done  as  soon  as  possi- 
ble after  receiving  them  at  the  mill,  the  object  being  to  separate  those 
of  the  proper  size  and  condition  for  pickling,  provided  that  branch  of 
the  industry  is  followed.  For  this  operation  there  are  numerous 
machines  in  use,  but  there  are  few  really  satisfactory  ones.  Most  of 
the  graders  bruise  the  fruit  to  such  an  extent  as  to  injure  it  for  pick- 
ling. One  of  the  most  successful  is  the  so-called  " Garvin  grader" 
(Fig.   6),   the  olives  destined  for  pickling  being  allowed  to  fall  into 


12 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION. 


buckets  partly  filled  with  water  to  break  the  fall  as  they  come  from  the 
machine.  The  grader  at  the  same  time  removes  much  trash  from  the 
olives,  the  removal  of  which  may  be  finished  by  the  use  of  a  blower,  as 
indicated  later  on.  An  ordinary  fanning-mill,  such  as  is  used  for 
cleaning  grain,  is  also  occasionally  used  for  the  removal  of  trash. 

For  the  making  of  oil  the  olives  should  be  washed  before  crushing,  in 
order  to  remove  adhering  dust  or  dirt,  lest  this  impart  a  disagreeable 
flavor  or  appearance  to  the  resulting  oil. 

THE    EXTRACTION    AND   CLARIFICATION    OF   THE    OIL. 

Drying. — There  are  some  working  difficulties  in  the  extraction  of  oil 
from  freshly-picked  olives,  and  in  order  to  facilitate    the  work   it   is 


Fig.  6.    The  Garvin  olive-grader. 


best  to  remove  a  portion  of  their  water,  either  by  allowing  them  to 
remain  on  the  trees  for  some  time  after  becoming  ripe  in  regions  where 
there  is  no  danger  from  frost,  and  thus  shriveling  them,  or  by  partially 
drying  them  subsequent  to  picking.  The  former  method  has  the  advan- 
tage of  requiring  less  labor,  and  at  the  same  time  there  is  an  apprecia- 
ble increase  in  the  percentage  of  oil  present  in  the  olives  so  wrinkled — 
more  than  the  increase  arising  from  the  loss  of  water — but  it  is  very 
questionable  whether  the  gain  in  the  quantity  of  oil  will  compensate 
for  the  loss  of  time. 

Drying  subsequent  to  picking  is  done  either  by  exposing  the  olives 
in  shallow  trays  to  the  action  of  the  sun  and  atmosphere,  or  by  means 
of  artificial  heat  in  a  drier  especially  constructed  for  the  purpose.     The 


CALIFORNIA   OLIVE    OIL.  13 

former  method  requires  from  fourteen  to  eighteen  days,  and  much  care 
has  to  be  taken  that  the  fruit  does  not  become  in  the  least  moldy.  In 
discussing  the  matter  of  drying  by  artificial  heat,  Mr.  Ellwood  Cooper, 
who  has  been  one  of  the  most  successful  of  oil-makers,  writes  as  follows: 
"This  plan  (sun-drying)  can  not  be  depended  upon  excepting  in  years 
when  the  fruit  ripens  early,  and  we  have  continuous  sunlight  with 
moderately  warm  weather.  By  artificial  heat  ranging  from  110°  to 
130°  F.,  the  drying  can  be  done  in  less  than  forty-eight  hours.  The 
crushing  and  pressing  should  follow  without  delay;  that  is,  the  fruit 
taken  from  the  drier  in  the  morning  should  be  crushed  and  pressed  the 
same  day.  Long  intervals  or  delays  in  the  process  from  picking  the 
fruit  to  expressing  the  oil  tend  to  rancidity.  To  make  perfect  oil  requires 
perfect  system  in  the  whole  management.  All  fruit  picked  during  the 
day  should  be  in  at  night,  cleaned  the  following  morning,  and  go  into 
the  drier  immediately  after  the  previous  day's  drying  is  out."  Mr. 
Cooper's  drier  has  a  capacity  of  about  one  ton  of  olives  per  charge,  or 
about  500  square  feet  of  surface,  which  is  equivalent  to  the  work  of 
about  five  pickers.  With  a  larger  press  and  mill  there  should  be  a 
corresponding  increase  in  the  drier  capacity.  The  temperature  in  the 
drier  should  not  exceed  130°  F.,  and  it  is  better  to  keep  it  somewhat 
below  that  point. 

Where  the  drying  is  done  without  artificial  heat  great  care  has  to  be 
taken  to  prevent  the  olives  from  becoming  in  the  least  moldy,  as  the 
slightest  indication  of  that  condition  will  ruin  the  oil.  Such  drying  is 
generally  done  by  placing  them  in  layers  not  more  than  three  inches 
deep,  on  trays  that  are  stacked  in  a  dry,  well-aired  room,  protected 
from  the  wind  and  the  direct  rays  of  the  sun.  The  olives  are  turned 
over  daily  until  they  become  well  wrinkled.  This  requires  about  eight 
or  ten  days,  according  to  the  degree  of  temperature.  If  the  partially 
dried  fruit  can  not  then  be  crushed  immediately,  it  must  be  stored  in  a 
dark  room  where  the  temperature  does  not  rise  above  60°  F.  Here  it 
may  remain  three  or  four  weeks  longer  without  any  serious  deteriora- 
tion in  the  quality  of  the  oil. 

Crushing  and  First  Pressing. — Considerable  improvement  in  the 
methods  of  crushing,  grinding,  and  pressing  has  been  made  during  the 
last  few  years.  The  old-fashioned  stone  mills,  with  their  slow,  cumber- 
some, and  irregular  action  and  driven  by  horsepower,  have  been  replaced 
by  the  more  effective  preliminary  crushing  by  means  of  corrugated 
bronzed  rollers  for  a  preliminary  treatment  of  the  olives,  which,  after 
a  first  pressing  to  remove  the  larger  part  of  the  water,  are  then 
subjected  to  the  more  thorough  grinding  by  means  of  massive  double 
or  single  edge  running  wheels  operated  by  power.  The  rollers  used  in 
the  mill  are  shown  in  Fig.  7,  and  the  entire  arrangement  of  blower, 


14 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT   STATION. 


mill,  and  elevators  in  Fig.  3.  These  rollers  are,  of  course,  inclosed  in  a 
suitable  feed  and  delivery  box,  as  shown  in  the  illustration  of  a  smaller 
type  of  the  same  machine  (Fig.  8).  This  crusher  is  so  arranged  that  it  can 
be  adjusted  at  will  to  crush  either  the  flesh  alone,  or  both  pits  and  flesh. 

Another  machine 
which  meets  with 
much  favor  is  a  so- 
called  "barley  crush- 
er," shown  in  Fig.  9. 
This  machine  is  very 
effective  and  is  often 
the  only  crushing  ma- 
chine used,  replacing 
entirely  the  edge-run- 
ner, but  not  to  advan- 


Fk;.  7.    Corrugated  rollers  used  for  crushing  olives. 


tage. 


The  first  pressing,  which  immediately  follows  this  crushing,  is  only 
designed  to  remove  the  water  of  vegetation  still  remaining  in  the  olives, 
and  for  this  reason  a  press  of  only  moderate  power  is  required.  In  a 
well-appointed  mill  the  crushed  olives 
will  fall  into  a  chute  immediately 
under  the  crusher,  or  upon  an  elevator 
delivering  to  the  car  of  the  first  press. 
The  first  arrangement  is  shown  in 
Fig.  2  (a)  and  the  latter  in  Fig.  3. 
There  are  various  types  of  presses 
used  for  this  first  pressing.  One  of 
the  best  which  has  come  to  the  writer's 
attention  is  shown  in  Fig.  10.  This 
type  of  press  is  sufficiently  powerful 
and  handles  large  quantities  of  ma- 
terial in  a  satisfactory  manner  for 
the  first  pressing,  but  is  not  powerful 
enough  for  the  last  pressing. 

As  shown  in  the  illustration,  the 
mass  of  olive  paste  is  placed  in  the 
press  in  such  a  manner  that  it  will 
constitute  a  series  of  layers,  each  of 
which  can  drain  off  horizontally  as 
the    pressure   is   supplied.      This    is 

accomplished,  among  other  ways,  by  means  of  wooden  gratings  and 
pieces  of  very  strong  cloth,  or  sacking,  placed  between  the  layers.  The 
<loth>  used  for  this  press  do  not  have  to  be  as  strong  as  for  the  later 
pressing.     A  very  serviceable  cloth  is  that  known  as  open-wove  Texas 


Fig.  h.    Small  olive-crusher. 


CALIFORNIA    OLIVE    OIL. 


15 


cotton,  which  costs  about  twenty  cents  per  square  yard.  By  this  press- 
ing the  bulk  of  the  mass  is  materially  reduced  and  its  handling  in  the 
powerful  press  much  facilitated  by  the  removal  of  the  larger  part  of  the 
water.  The  pressure  should 
be  applied  very  gradually. 
There  is  great  temptation 
to  hurry  the  pressing,  but 
such  forcing  of  the  work 
only  results  in  disappoint- 
ment at  the  results  ob- 
tained, since  time  is  the 
element  here  for  the  effect 
to  be  realized  upon  the 
mass.  From  the  liquid 
which  runs  out  at  this 
pressing  is  made  the  often 
talked  of  but  seldom  seen 
;  virgin  oil."  In  Califor- 
nia practice  it  is  rare  in- 
deed that  this  is  made,  this 
liquid  being  passed  rapidly 
through  the  washer  (see 
page  20),  and  the  oil  being- 
collected  and*  mixed  with 
that  from  the  next  pressing. 
After  the  removal  of  the  liquid  by  light  pressure,  the  full  power  of 
the   machine  is  gradually  brought  to  bear  upon  the  mass.     A  hand- 

p]  screw  press  is  sometimes  used  for 
this  first  pressing,  but  the  greater 
economy  of  time  and  labor  by  the  use 
of  a  power  press  probably  warrants 
the  extra  small  cost  over  a  first-class 
hand  press,  if  the  work  is  to  be  under- 
taken in  any  except  a  small  way. 
Under  the  latter  condition  the  small 
grinder  and  press  shown  in  Figs.  11 
and  12  serve  good  purpose. 

The  small  mill  consists  of  a  round 

box  mounted  on   a  light  frame  and 

having  a  hopper  in  the  center  of  its 

top    through    which    the    olives    are 

fed.     The  crushing  is  done  by  a  rotary  plate,  placed  inside  this  box, 

which  is  corrugated  or  ribbed  as  shown  and  operates  to  grind  the  olivee 

as  they  are  caught  between  it  and  the  under  surface  of  the  box  cover. 


Kg*  i  m 

jge. 

_^^m                         '^W 

'  f  " 

HP  ^| 

$p>- 

^S- 

'tff   ■        A 

5ran 

%lW& 

1       -m     ^K 

L-~-~_~~.-_.Jj 

^B  'jE§  vGfBm 

■  J* 

M^ujam  ., 

imMmJ&'M 

la' 

,J       '% 

->f  • 

* 

..::r^^.^ 

MM-fe 

-u-^ 

Fig.  9.    Barley-crusher  used  for  crushing  olives. 


Fig.  10.    Automatic  press  for  first  pressing. 


16 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION. 


which  is  also  corrugated  to  match.  This  rotary  plate  is  turned  by  a 
spindle  passing  through  the  bottom  of  the  box,  and  is  geared  with  a 
short  shaft  that  is  run  by  a  flywheel  and  crank,  as  illustrated;  or  else 
by  a  belt-pulley  when  power  is  available.     The  spindle  of  the  rotary 

plate  is  adjustable  vertically,  so 
that  this  grinding  plate  may  be 
brought  more  or  less  close  to  the 
top  of  the  box  and  made  to  per- 
form the  crushing  to  suit;  the 
crushing  being  more  or  less  fine 
according  to  its  distance  from  the 
top  of  the  box.  The  corrugations 
or  ribs,  it  will  be  seen,  are  curved 
from  center    to    rim,    forming   be- 


Fig.  11.    Small  olive-crusher. 

tween  them  curved  grooves  in 
which  the  olives  are  lodged  and 
their  pits  or  stones  stripped  of 
flesh  as  the  ribs  of  the  plate  and 
box  pass  or  cross.  The  cor- 
rugations in  the  top  of  the  box 
run  in  a  direction  opposite  to 
that  of  the  corrugations  of  the 
rotary  plate.  The  adjustment 
of  the  rotary  plate  can  be  so 
nicely  regulated  that  the  pits  I 
contained  in  its  grooves  will  not  HJ 
be  crushed,  thereby  always  in-H 
suring  a  sweet  paste  and  conse-H 
quently  an  oil  of  higher  grade. 
In  order  to  prevent  clogging  and 
to  insure  a  constant  discharge,  a  feed-screw  is  provided,  located  cen- 
trally inside  the  hopper. and  socketed  in  the  rotary  plate  so  as  to  be 
turned  thereby.  This  screw  drives  down  the  olives  as  they  are  fed  into 
the  hopper  and  thus  creates  a  forcing  feed,  the  effect  of  which  is  to  clear 


Fig.  12.    Oil  press. 


CALIFORNIA    OLIVE    OIL. 


17 


the  mill  of  the  mashed  olives  and  crowd  out  the  latter,  as  fast  as  they  are 
being  crushed,  toward  the  sides  of  the  box;  where  they  fall  off  the  edge  of 
the  rotary  plate  and  drop  below  it  into  the  bottom  of  the  box.  Thence 
the  crushed  olives  are  taken  up  by  scrapers  secured  to  the  under  side 
of  the  rotary  plate,  and  are  carried  round  and  pushed  into  the  dis- 
charge opening  and  out  of  the  spout  into  a  bucket  placed  underneath  to 
receive  them.  The  little  mill  is  made  of  iron,  suitably  tinned,  and  has 
a  crushing  capacity  of  one  hundred  pounds  per  hour. 

The    Grinding  and   Second   Pressing. — The  pulp  on  being  removed 
from  this  press  is  thoroughly  broken  up  in  a  limited  quantity  of  water, 
and     delivered    to 
the    edge  -  running 
grinder,   which  re- 
duces it  to  a  very 
fine  condition.  The 
finer  the  condition 
of    this    pulp    the 
larger   will  be  the 
quantity  of  oil  re- 
covered,     other 
things  being  equal. 
However,  some  pre- 
fer not  to  crush  the 
pits  in  either  grind- 
ing,   owing  to  the 
fact  that  it  is  sup- 
posed    that     they 
carry    an    inferior 
quality  of  oil,  which 
tends     to     become 
rancid  sooner  than 
that  in  the  flesh  of 
the  olive.     There  are  few,  however,  in  actual  practice  who  do  not  crush 
the  pits,  and  from  a  practical  standpoint  it  is  an  open  question  whether 
the  extremely  small  amount  of  oil  carried  by  the  pits  impairs  the  oil 
sufficiently  to   have  any   material  effect   upon  it  in  commerce  if  the 
other  precautions  of  manufacture  are  carefully  observed.     Edge-runners 
can  be  so  regulated  as  to  do  either  the  one  or  the  other  as  may  be 
desired.     A  modern  edge-runner,  together  with  a  powerful  hydraulic 
press,  is  shown  in  Fig.  13. 

Edge-runners  may  be  had  with  the  gearing  either  above  or  below. 
There  is  no  difference  in  the  effectiveness  of  the  one  over  the  other,  and 
the  type  to  be  employed  is  largely  determined  by  the  available  space. 
These  edge-runners  may  be  had  with  either  double  or  single  rollers, 


Fig.  13.    Bottom-geared  edge-runner. 


18  UNIVERSITY    OF   CALIFORNIA — EXPERIMENT    STATION. 

which  may  in  either  case  be  reudily  adjusted  to  meet  the  needs  of  the 
various  conditions  and  sizes  of  the  olives  being  worked. 

The  mills  may  be  had  in  four  styles,  similar  in  appearance  but  differ- 
ing in  the  materials  of  which  they  are  constructed.  The  most  common 
is  the  cast-iron  mill,  but  this  is  open  to  the  serious  objection  of  being 
very  difficult  to  keep  clean.  Inasmuch  as  the  use  of  metal  is  open  to 
some  objection,  similar  mills  are  made  entirely  of  granite,  but  their  cost 
is  much  higher.  A  very  good  substitute  for  the  latter,  and  perhaps 
equally  good  for  all  practical  purposes,  is  one  with  rollers  and  pan 
bottom  made  of  granite,  with  sides  of  the  pan  of  artificial  stone  bound 
with  iron  and  firmly  set  to  the  granite  bottom  of  the  pan.  It  possesses 
the  advantages  of  not  bringing  iron  into  contact  with  the  mass,  and  at 
the  same  time  of  being  much  cheaper.  The  mills  are  furnished  with 
mold  boards,  which  follow  the  path  of  the  olives  and  constantly  turn 
them  over  and  thereby  secure  an  even  grinding.  The  character  of  the 
grinding  has  much  to  do  with  the  effectiveness  of  the  pressing.  The 
paste  secured  must  be  fine  and  of  even  consistency. 

From  the  edge-runner  the  pulp  is  delivered  to  the  second  press  by 
means  of  a  link-belt  elevator,  as  shown  in  Fig.  14,  through  a  measuring 
chute  as  in  the  case  of  press  No.  1.  The  press  here  used  is  best  operated 
by  hydraulic  power,  and  may  be  had  of  various  sizes  and  pressures. 
The  pressures  generally  employed  develop  a  total  pressure  of  about  400 
tons  on  an  area  of  36  inches  by  60  inches,  thus  giving  a  pressure  of 
about  370  pounds  per  square  inch.  The  quantity  of  water  required  for 
the  press  is  very  small.  It  will  be  seen  that  there  are  two  cars  with 
this  press  as  with  the  other,  so  arranged  that  while  one  is  being  pressed, 
the  other  is  being  emptied  and  refilled  from  the  chute  leading  from  the 
edge-runner,  so  the  press  can  be  kept  constantly  in  operation.  The 
edge-runner,  elevator,  and  press  in  operation  may  be  seen  in  the  illus- 
tration of  the  mill  of  the  Los  Angeles  Olive-Growers'  Association. 
(Fig.  14.) 

The  cloth  used  upon  this  press  requires  to  be  much  stronger  than  in 
the  first  case.  Russian  "Red  Raven"  linen  press  cloth  has  given 
excellent  satisfaction,  the  cost  of  which  is  about  $2.25  per  square  yard. 

The  oil  removed  by  this  second  pressing,  after  clarification,  consti- 
tutes essentially  the  "California  Olive  Oil"  of  commerce,  as  few  opera- 
tors go  so  far  as  to  give  a  third  pressing. 

Under  the  ordinary  practice  in  this  State,  investigation  shows  that 
only  from  one  third  to  one  half  of  the  oil  contained  in  the  olive  is 
removed  by  pressings,  thus  showing  the  heavy  loss  of  material  which 
the  industry  must  sustain.  There  is  little,  if  any,  attempt  made  to 
remove  the  residual  oil  for  any  purpose  at  present.  From  reports 
received  from  the  most  extensive  olive-oil  makers  in  the  State,  the  fig- 
ures being  based  upon  the  season's  work,  i.  e.,  the  total  quantity  of  olives 
worked  for  oil  and  the  total  weight  of  the  product,  it  appears  that  the 


CALIFORNIA    OLIVE    OIL 


19 


recovery  ranges  from  25  to  40  gallons  of  oil  per  ton  of  olives.  One  of 
the  most  experienced  makers  puts  it  this  way:  "My  average  is  56 
pounds  of  olives  to  the  gallon  of  oil." 

The  pulp  remaining  from  this  pressing  makes  a  most  excellent  hog 


or  chicken  food,  and  also  a  most  excellent  fuel.  In  those  localities 
where  fuel  is  scarce  and  high  it  may  well  be  used  for  this  purpose  for 
operating  the  mill,  furnishing  nearly  if  not  quite  enough  fuel  for  the 
entire  operation. 


20 


UNIVERSITY    OF   CALIFORNIA EXPERIMENT    STATION. 


AND  OIL        1 
T0BEWA$HED.jk 


WATER  SUPPLY. 


am  oil 


The  oil  from  this  pressing,  as  well  as  that  from  the  first,  is  separated 
as  rapidly  as  possible  from  the  black  water  which  accompanies  it.  This 
is  most  effectively  done  by  means  of  the  oil  washer  (Fig.  15).  The 
employment  of  this  apparatus  is  a  great  improvement  over  allowing 
the  press-liquid  to  settle  in  tinned  vessels  alone  and  removing  the  oil 
by  skimming.  It  makes  the  separation  of  the  oil  almost  instantaneous, 
and  improves  the  quality  by  doing  away  with  the  prolonged  contact  of 
the  oil  with  the  air  and  the  impurities  of  the  liquid.  The  juices  from 
the  press  flow  into  a  tube,  which  opens  into  a  small  "drum"  near  the 
bottom  of  the  tank,  which  is  kept  constantly  full  of  water.  This  drum 
,_      jw,  is  perforated  at  the  sides  in 

OLIVE  JUICE  %  order  to  allow  the  press-liquid 

to  escape  horizontally.  Im- 
mediately above  this  drum 
is  another  larger  one,  per- 
forated on  the  bottom,  through 
which  water  is  forced  in  jets. 
The  water  and  press-liquid 
are  thus  thoroughly  mixed  in 
constant  agitation.  This  re- 
sults in  the  rapid  deposition 
of  the  heavy  impurities,  and 
the  equally  rapid  rise  of  the 
small,  light  oil-drops.  The 
oil  very  quickly  forms  a  layer 
on  top  and  can  be  drawn  off 
by  means  of  a  faucet  appro- 
priately placed.  The  appa- 
ratus is  continuous  in  its 
operation,  and  the  oil  is  ob- 
tained free  from  all  the  gros- 
ser impurities.  It  is  still, 
however,  very  cloudy,  owing 
to  the  presence  of  small,  light  particles  of  vegetable  matter. 

"Clarification. — The  oil  must  be  made  as  bright  as  possible  before 
being  put  upon  the  market.  This  can  be  done  by  various  methods 
of  filtration.  Filtration,  however,  diminishes  the  freshness  and 
aroma  of  the  oil  and  injures  the  qualities  that  distinguish  a  fine 
olive  oil  from  the  clear,  neutral  oils  extracted  from  cotton-seed.  This 
is  especially  true  of  such  filtering  media  as  charcoal,  which  exert  some 
absorbent  influence  upon  the  oil,  diminishing  its  flavor.  The  best 
method  of  clearing,  for  oil  as  for  wine,  is  by  simple  settling  and  decan- 
tation.  For  this  purpose  a  series  of  settling  tanks  is  made  use  of. 
These  may  be  made  of  well-tinned  metal,  or  of  cement  lined  with  glass 


FORftMAr// 
MTERLEVEL 


FQRCLfAMM 


Fig.  15.    Olive-oil  washer. 


CALIFORNIA   OLIVE    OIL. 


21 


or  other  impervious  substance.  For  small  plants  the  first  settling  is 
conveniently  made  by  means  of  a  funnel-shaped  apparatus  such  as  that 
shown  in  Fig.  16.  The  steeply  conical  shape  facilitates  the  rapid  depo- 
sition of  sediment.  After  standing  for  twenty-four  hours  in  this  appa- 
ratus the  major  part  of  the  sediment  is  deposited  and  can  be  drawn  off 
at  the  bottom.  It  is  well,  before  running  the  oil  into  the  settling  tanks, 
to  pass  it  through  two  or  three  inches  of  cotton  wool.  This  is  accom- 
plished by  means  of  a  funnel  with  a 
perforated,  horizontal  cross-partition, 
upon  which  the  cotton  is  placed.  It 
takes,  generally,  about  one  month  for 
the  oil  to  settle  sufficiently  in  the  first 
tank,  after  which  it  should  be  drawn 
off  carefully  into  the  second,  and  so  on 
until  it  is  sufficiently  bright.  Three 
rackings  are  usually  sufficient,  and  if 
all  parts  of  the  process  have  been  well 
attended  to,  an  oil  is  obtained  almost 
as  bright  as  can  be  produced  by  the 
most  effective  method  of  filtration,  and 
having,  besides,  the  agreeable  and  dis- 
tinctive olive  flavor  and  absence  of 
greasiness  which  is  lacking  in  all  filtered 
oils."* 

Filtering. — It  is  not  at  all  essential  to 
filter  oil  in  order  to  obtain  a  perfectly 
clear  and  bright  product.  The  writer 
has  seen  unfiltered  California  olive  oil 
which  had  been  bottled  ten  years  and 
Avas  still  as  clear  and  bright  as  when 
first  put  up.  The  essential  element  in 
obtaining  such  oil  is  time  in  which  to 
obtain  a  perfect  racking.  If  sufficient 
time  is  not  allowed  a  sediment  will 
certainly  settle  in  the  bottles,  which 
will  as  certainly  spoil  the  market  value  of  the  oil.  While  the  separa- 
tion of  this  sediment,  or  the  separation  of  the  solid  fats,  is  not  a 
sign  of  an  impure  oil,  but  on  the  contrary  is  presumptive  evidence  of 
a  pure  oil,  yet  either  is  fatal  to  the  market  qualities  of  the  oil.  By  the 
use  of  an  effective  method  of  filtration  it  is  certainly  possible  to  place 
the  oil  on  the  market  sooner  than  without  such  filtration;  yet  unless 
this  filtration  be  extremely  good  there  may  still  be  a  gradual  collection 


Fig.  16.    Oil  funnel. 


*  Bulletin  No.  137,  California  Experiment  Station. 


22 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 


b  Closed. 

The  International  Filter. 


of  sediment.     One   of  the  most  effective  filters  which  the  writer    has 

found  in  use  is  known  as  the  "International  Filter"  (Fig.  17). 

This  filter  is  in  use  by  one  of  the  best  oil- 
makers  in  the  State,  and  he  states  that  it  has 
given  entire  satisfaction.     The  filter  consists 

of  two  shells,  hinged 
together,  and  clamped 
around  the  edge  by 
means  of  hand  bolts. 
The  inlet  is  in  the 
lower  shell,  the  outlet 
in  the  upper  one,  and 
the  filtering  is  accom- 
plished by  means  of 
filter  discs  locked 
securely  around  the 
edge  between  the  two 
shells.  The  filtration 
is  upward,    which   is 

particularly  advantageous,  as  the  heavier  particles  tend  to  settle  away 

from  the    discs  instead  of   clogging  them.       There  are   no    corners  or 

small     passages,    so     that 

every  portion  of  it  may  be 

reached      for      thoroughly 

cleansing,    and    there  is  a 

minimum    of    exposure    to 

air.    It  occupies  little  space 

and  can  be  operated  either 

by  pump,  or  in  the  case  of 

olive     oil     preferably     by 

gravity.     The  filter  can  be 

had  in  brass,  block -tinned 

throughout. 

The  more  common  form 

of  filtration  is  by  means  of 

tin  or  glass  funnels  fitted 

with     filter     paper.        The; 

most    efficient    paper    will 

be  found    to     be    No.    595, 

S.  cV:  SC,  which  may  be  had 

either     in     sheets     or    cut 

round   in  the  desired   size. 
Mr.   Ellwood  Cooper  writes: 

series  of  five  or  six  boxes,  one  above  the  other,  each  with  cotton  batting 


Fig.  is.    Settling  tanks  surmounted  with  filters. 
"The  most  common  method  is  to  have  a 


CALIFORNIA    OLIVE    OIL. 


23 


in  the  bottom.  The  oil  passing  the  sixth  will  be  beautifully  clear  and 
ready  for  market.  I  use  cylindrical  vessels  holding  about  three  gal- 
lons each,  one  fitting  in  the  other,  in  tiers  of  three,  with  fine  wire  sieve- 
in  the  bottom  of  each.  On  these  sieves  I  place  two  or  three  layers 
of  cotton  batting.  The  oil  is  passed  from  one  tier  to  the  other  until 
clear."     (Fig.  18.) 

A  very  effective  system  of  final  filtration  in  use  by  one  of  the  larger 
mills  is  shown  in  the  accompanying  illustration  (Fig.  19).  The  oil 
after  having  passed  through  a  preliminary  filtration  is  racked  off 
several  times  and  finally  passed  through  the  filter  shown.     These  niters 


Fig.  19.    Sand  filter  for  oil. 

are  arranged  in  triplicate  in  the  mill  in  question.  In  this  mill  the  oil 
is  drawn  off  from  the  final  racking  tanks,  which  hold  about  five  hun- 
dred gallons  each,  arranged  on  a  platform  of  sufficient  height  to  allow 
another  tank,  rectangular,  resting  upon  trucks  which  also  bear  a  small 
"Challenge"  pump,  to  be  placed  beneath  so  as  to  receive  the  oil  as  it  is 
drawn  off.  (The  racking  tank,  as  well  as  the  transfer  truck  and  tank, 
together  with  pump,  are  shown  in  Fig.  20.)  From  the  transfer  tank 
the  oil  is  pumped  to  a  common  supply  tank  located  on  a  floor  above 
the  niters.  The  delivery  is  by  a  common  supply  pipe  delivering  to  the 
three  filters  separately,  as  shown  in  the  drawing.  The  oil  first  passes 
through  eight  or  ten  inches  of  sand,  and  finally  through  several  inches 
of  the  best  grade  of  cotton  waste.     The  filtration  is  rapid  and  the  prod- 


24 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 


net  comes  out  in  a  fine,  clear  condition.  The  filters  are  about  4^  feet 
high  and  2-J  feet  wide  at  the  widest  portion,  and  the  three  have  a  capa- 
city of  about  three  hundred  gallons  of  oil  in  twenty-four  hours. 

The  tendency  among  most  makers  of  olive  oil  is  to  attempt  to  bottle 
the  oil  too  soon.  While  the  oil  will  usually  appear  perfectly  clear  after 
three  rackings  at  intervals  of  a  month  each,  yet  when  bottled  under 
these  conditions  a  fine  sediment  usually  settles,  which  not  only  affects 
the  market  value  of  that  particular  brand,  but  also  has  an  indirect 
influence  on  all  California  oils.     Where  racking  alone  is  depended  upon 

for  clarification,  oil  should  not  be 
bottled  in  a  shorter  time  than  six 
months. 

CENTRIFUGAL  EXTRACTION  OF  OIL. 

In  the  common  method  of  extrac- 
tion by  pressure  there  are  many 
difficulties  which  present  themselves 
and  tend  to  increase  the  cost  of 
manufacture.  Among  these  may  be 
mentioned  the  duplication  of  presses, 
the  time  required,  the  low  yield  of 
oil,  and  the  inconvenience  of  the 
cloths,  or  "scoutins,"  as  the  case  may 
be,  for  holding  the  pulp. 

As  already  pointed  out,  in  order  to 
secure  a  sufficient  pressure,  it  is  neces- 
sary either  to  operate  two  presses,  one 
of  medium  and  one  of  high  power,  or 
in  lieu  of  this,  to  subject  the  mass 
to  two  pressings,  at  the  expense  of 
time.  In  the  preliminary,  or  first,  pressing  no  attempt  is  made  to 
remove  oil,  but,  as  already  pointed  out,  to  remove  a  larger  part  of  the 
free  water,  in  order  that  the  mass  may  stand  up  better  in  the  press. 
Under  pressure  the  yield  is  far  less  than  is  desired.  Considerable 
pains  have  been  taken  to  ascertain  as  closely  as  possible  what  is  the 
usual  yield  of  oil  in  this  State  when  the  extraction  is  conducted  under 
the  usual  conditions  as  represented  both  by  the  average  practice  and 
when  the  highest  efficiency  was  employed.  The  results  of  this  investi- 
gation show  as  follows: 


Fig.  20.    Racking  tanks  and  transfer  car. 


Percentage  of  Oil  in  Pressed  Pulp.  Per  Cent. 

Mill  No.  1 J 13.5 

Mill  No.  2 10.7 

Mill  No.  3 11.8 

Mill  No.  4 17.0 

Mill  No.  5 16.0 

Mill  No.  (J i 14.0 


CALIFORNIA    OLIVE    OIL.  25 

In  this  connection  we  have  no  means  of  knowing  accurately  just 
what  may  have  been  the  oil  content  of  the  original  olives,  but  as  a 
maximum  it  could  not  be  assumed  that  they  averaged  more  than  30 
per  cent  oil,  nor  less  than  20  per  cent  as  a  minimum. 

Looking  at  the  matter  from  the  recoveries  in  oil  reported,  and  using 
only  those  which  are  based  upon  the  weight  of  the  oil  turned  out  dur- 
ing the  season's  run  and  the  olives  received  and  pressed,  and  taking  the 


Fig.  21.    A  Weston  Centrifugal  Machine. 

same  range  of  oil  content  of  the  olives  as  above  stated  (20  to  30  per 
cent),  we  find  as  follows: 

Gals.  Oil  Minimum  Maximum 

per  Ton  Recovery.  Recovery. 

Mill  No.  1 30  to  40  48.5%  65.0% 

Mill  No.  2 80  32.5  48.5 

Mill  No.  3 30to40  48.5  65.0 

Mill  No.  4 ^ 40  45.0  65.0 

Mill  No.  5 32  34.6  52.0 

Mill  No.  6 40  45.0  65.0 

Mill  No.  7 36  39.0  58.5 

Mill  No.  8 32  34.6  52.0 

Judging  from  the  above  we  can  fairly  say  that  the  range  of  recovery 
under  the  ordinary  practice  in  the  State  is  only  about  35  to  65  per 
cent  of  the  oil  contained  in  the  olive;  or  in  other  words,  a  loss  exceed- 
ing one  half  of  the  oil  contained  in  the  olives. 


26 


UNIVERSITY    OF   CALIFORNIA EXPERIMENT    STATION. 


Speaking  along  this  line  a  foreign  journal  says:  "The  yield  from 
pressure  is  low;  the  quantity  of  oil  extracted  by  two  pressings  is,  as  a 
maximum,  20  per  cent  of  the  olive  (ordinarily  15  to  18  per  cent)  when 
the  fruit  contains  30  per  cent."  Thus  showing  a  loss  of  from  50  to  66 
per  cent  of  the  oil  present. 

Further,  the  employment  of  bags  or  grass  mats  for  holding  the  pulp 
is  accompanied  with  several  inconveniences,  among  which  may  be 
mentioned  the  imparting  of  a  certain  taste  and  color  foreign  to  the  oil 
itself.  They  absorb  considerable  oil  during  the  course  of  the  work,  and 
unless  extreme  care  be  taken  this  becomes  rancid  and  contaminates  the 
oil.  They  wear  out  rapidly,  and  their  replacement  is  expensive.  The 
filling  of  them  with  the  olive  paste  requires  much  care  and  labor.     If 

too  full,  the  oil  remains  in  large  quantity. 
If  the  distribution  is  irregular  the  pressure 
is  unequal  and  it  becomes  difficult  to  hold 
the  column  upright  in  the  press. 

To  overcome  the  difficulties  mentioned 
above  one  of  the  most  recent  suggestions 
has  been  to  employ  in  the  place  of  presses 
centrifugals  as  in  a  sugar  factory,  where 
they  are  used  to  separate  the  molasses 
from  the  crystals.  The  method  has  met 
with  some  success  in  Algeria,  and  a  num- 
ber of  mills  in  that  country  have  intro- 
duced such  machines.  For  other  work  in 
separation  and  drying  these  machines  are 
used  in  many  industries.  The  machine 
consists  essentially  of  a  perforated  cylindri- 
cal metal  basket  turning  in  a  casing  which 
envelops  it.     The   details   of  the  arrange- 

Fig.  22     Section  of  a  Centrifugal,    ment  ,    the    gtandardg  for    supporting 

showing  basket,  curbing,  and  screens.  '  *  rr  ° 

it,  are  shown  in  Fig.  22,  and  the  machine 
actually  used  is  shown  in  Fig.  21. 

The  machine  used  was  made  by  the  American  Tool  and  Machine 
Company,  Boston,  and  admirably  served  the  purpose  for  the  prelim- 
inary experiments,  although  in  such  a  small  machine  the  work  would 
have  been  facilitated  somewhat  if  the  basket  had  been  swung  from 
the  bottom  rather  than  from  the  top,  thus  leaving  the  top  open  and 
free  for  work;  which,  however,  is  not  a  vital  point  in  larger  machines 
as  used  in  the  sugar  house. 

The  basket  of  this  machine  was  ten  inches  in  diameter  and  six  inches 
deep,  the  inside  being  lined  in  some  cases  with  a  single  screen,  at  other 
times  with  two  screens  of  different  mesh,  and  at  still  other  times  there 
was  added  a  cloth  for  the  purpose  of  holding  back  more  effectually  the 


CALIFORNIA    OLIVE    OIL. 


27 


fine  pulp,  and  of  giving  a  preliminary  filtering  at  the  same  time  that 
the  oil  was  separated  from  the  pulp.  The  machine  was  belted  to  a  1^- 
horsepowrer  electric  motor  in  such  a  manner  that  it  was  possible  to  run 
the  basket  at  a  speed  of  three  thousand  times  per  minute. 

In  the  season  of  1902  the  experiments  were  begun  so  late  that  it  was 
impossible  to  become  sufficiently  familiar  with  the  machine  and  the 
methods  of  screening  as  to  secure  reliable  results,  and  practically  all 
the  time  was  spent  in  preliminary  work  which  had  only  an  indirect 
bearing  upon  the  question  in  hand.  In  1903,  however,  definite  work 
was  outlined  and  carefully  conducted,  and  the  results  are  subjoined. 

Work  of  Small  Centrifugal. 


a 
5" 

OS 

Run. 

Weight 
of  Olives. 

Weight 
of  Pulp. 

Oil  in 
Pulp  (or 
Olives). 

Water 
in  Pulp. 

Solid 
Matter 
in  Pulp 

(or 
Olives). 

Weight 

of  Oil 

in  Pulp 

(or  Oil). 

Total 
Oil  Lost 
in  Pulp. 

Total 
Oil 
Recov- 
ered. 

Time. 

4 

Olives 
1 
2 
3 

lbs. 
500 
500 
500 
500 

lbs. 

Per  cent. 

24.6 

13.6 

6.1 

14.9 

Per  cent. 
55.4 
36.4 
19.4 
41.3 

Per  cent. 
20.0 
50.0 
74.9 
43.8 

lbs. 
123.0 
38.1 
16.3 
41.3 

Per  cent. 

Per  cent. 

min. 
30 

280.8 
267.2 

258.8 

31.9 
13.2 
34.6 

68.1 
86.8 
66.4 

30 
30 

30 

Average . 

500 

1000 
1000 

268.9 

11.5 

32.7 

55.8 

32.3 

26.2 

73.8 

B   1!       2 

555.2 
538.0 

14.1 
15.7 

40.1 
42.1 

45.8 
42.2 

78.3 

84.5 

31.4 
34.4 

68.6 
65.7 

Average . 

1000 

546.6 

14.9 

41.1 

44.0 

81.4 

32.8 

67.1 

c! 

1 

1 
2 

3 

1500 
1500 
1500 

933.6 
854.1 
762.0 

13.5 
15.9 
14.1 

44.0 
40.6 
37.2 

42.5 
43.7 

48.7 

126.0 
135.8 
107.4 

31.1 
36.8 
26.4 

65.9 
63.2 
73.6 

Average  _ 

1500      1       849.9 

14.5 

40.2 

45.3 

123.0 

32.4 

67.6    | 

M 

1 
2 
3 

2000 
2000 
2000 

1042.4 
1029.3 
1060.1 

15.1 

14.8 
11.9 

44.2 
46.2 
40.7 

40.7 
39.0 
47.4 

157.4 
152.3 
126.1 

31.9 
30.9 
25.8 

68.1 
69.1 
74.2 

Average  _ 

2000 

1043.9 

13.9 

43.7 

42.4 

145.2 

29.5 

70.5 

E 

1 

1 
2 

3 
4 
5 

2000 

963.4 

16.7 

41.8 

41.5 

160.9 

32.7 

67.3 

f 

• 

1 
I 

1740 
1740 
1740 
1740 
2960 

952.1 
885.3 
841.7 
975.5 
1574.0 

14.8 
15.9 
8.5 
14.4 
13.2 

41.5 
35.2 
39.4 
38.4 
40.8 

43.7 

48.9 
48.9 
52.8 
54.0 

140.9 
140.7 
72.5 
140.5 
207.7 

32.7 
32.7 
16.9 
32.6 
27.1 

67.3    1 

67.3     

83.1     

67.4     

72.9     

A^ 

^erage . 

1984           1045.7 

1 

13.3 

39.1 

47.6 

140.4 

28.4 

71.6     

The  experiments  were  divided  into  several  series,  each  of  which  was 
made  up  of  several  runs.  In  series  A,  B,  C,  D,  Nevadillo  olives  from 
Dinuba  were  used.  The  olives  were  in  good  condition  and  were  dried 
until  they  became  moderately  wrinkled  in  appearance  before  working, 
and  at  this  time  carried  the  amount  of  oil  indicated  in  the  first  table. 


28  UNIVERSITY    OF   CALIFORNIA— EXPERIMENT   STATION. 

Seventeen  per  cent  of  these  olives  consisted  of  pit  at  the  time  of  the 
experiment.  In  this  series  the  olives  were  first  passed  through  a  con- 
tinuous-acting Enterprise  fruit-crusher,  the  end  cap  of  which  was 
removed  to  allow  the  pits  to  escape. 

This  machine  does  not  crush  the  pit,  and  for  a  very  limited  number 
of  olives  works  quite  satisfactorily  where  it  is  desired  not  to  crush  the 
pit,  but  for  use  in  a  centrifugal  the  flesh  is  not  worked  to  a  sufficiently 
fine  condition  by  this  grinder.  The  several  series  here  presented  were 
run  with  varying  amounts  of  pulp  to  determine  somewhat  definitely 
the  largest  possible  charge  which  could  be  worked  to  advantage  in  the 
small  machine,  and  at  the  same  time  to  ascertain  the  efficiency  of  the 
operation  generally. 

The  greater  part  of  the  liquid  (mixture  of  oil  and  water)  is  expelled 
during  the  first  five  minutes,  or  about  one  half  of  the  total  which  can  be 
obtained  by  this  method.  The  operation  is  continued,  however,  and  in 
from  thirty  minutes  to  forty-five  minutes  about  65  per  cent  of  the  total 
can  be  obtained,  depending  somewhat  upon  the  condition  of  the  olives 
and  the  thoroughness  of  the  grinding. 

At  the  outset  of  these  experiments  it  was  shown  that  the  wire  screen 
alone  was  entirely  inadequate  to  hold  back  the  pulp,  and  several  trials 
were  made  with  different  kinds  of  cloth  placed  beneath  the  screen, 
between  it  and  the  outer  basket,  which  finally  resulted  in  the  adoption 
of  a  light-weight  flannel  as  giving  the  most  efficient  result.  The  con- 
trast in  the  character  of  the  centrifuged  liquid  with  and  without  the 
cloth  filter  in  the  machine  is  shown  by  the  following  composite  samples 
of  "extract"': 

Pulp  in  "  Extract." 

With  single  wire  screen  only 22.7  percent. 

With  screen  underlaid  with  flannel 5.6  per  cent. 

Inasmuch  as  this  pulp  gives  much  trouble  in  the  clarification  and  its 
presence "  causes  serious  losses  of  oil,  the  importance  of  the  above 
arrangement  is  manifest,  and  in  all  subsequent  work  the  flannel  was 
employed. 

Contrasting  the  results  from  this  machine  with  those  indicated  above 
from  pressing,  it  is  easily  seen  that  the  showing  is  quite  favorable  to 
the  centrifugal  method,  yet  is  not  as  favorable  as  expected  from  the 
reports  in  the  foreign  publications  mentioned  above. 

"There  is  obtained  thus,  in  about  ten  minutes,  a  total  yield  of  as 
"  high  as  90  per  cent,  depending  upon  the  grinding  of  the  olive." 

"The  ripe  olives  containing  on  an  average  25  per  cent  of  water  of 
"  vegetation  and  30  per  cent  of  oil,  or  a  total  of  55  per  cent  of  liquid, 
"  and  the  water  of  vegetation  being  expelled  during  the  first  few  minutes, 
"  the  yield  of  90  per  cent  indicated  is  proportioned  as  follows  upon  100 
"  kilos  of  olives:  25  kilos  of  water  of  vegetation  and  24  kilos  of  oil." 


CALIFORNIA   OLIVE    OIL.  29 

In  these  experiments  there  was  experienced  considerable  difficulty 
from  the  packing  of  the  pulp  closely  down  upon  the  screen,  thus  inter- 
fering with  the  free  flow  of  the  oil  and  water,  especially  the  former,  and 
it  was  found  that  more  efficient  results  could  be  obtained  by  loosening 
the  pulp  from  the  sides  of  the  machine  each  fifteen  minutes. 

The  action  of  the  mass  in  the  machine  suggested  the  desirability  of 
modifying  the  latter  to  some  extent  so  as  to  allow  a  certain  portion 
of  the  oil  to  escape  from  the  central  portion  of  the  basket  rather  than 
to  force  it  through  the  mass.  This  arises  from  the  fact  that  at  the 
outset,  as  the  basket  is  set  in  motion,  the  water  is  of  course  thrown  out, 
and  on  account  of  the  difference  in  the  specific  gravity  of  the  oil  as 
compared  with  that  of  the  pulp  and  the  water  its  first  tendency  is  to 
separate  on  the  inside  of  the  basket,  and  if  after  running  the  machine 
about  fifteen  minutes  it  be  stopped  a  considerable  quantity  of  pure  and 
clear  oil  will  be  found  to  have  separated  itself,  which  could  be  drawn 
off,  provided  there  was  some  satisfactory  method  of  doing  so.  With 
these  machines,  as  constructed,  however,  this  can  not  be  well  done,  and 
the  oil  which  has  once  been  separated  in  this  way  has  to  be  driven 
through  the  mass  now  packed  against  the  screen,  thus  requiring  double 
work.  It  was  not  feasible  at  this  time  to  so  modify  the  machine  as  to 
allow  this,  and  consequently  the  work  was  conducted  by  driving  the  oil 
through  the  mass  by  sheer  centrifugal  force,  after  the  removal  of  the 
water. 

With  this  idea  of  causing  the  oil  to  come  to  the  interior  more  effectu- 
ally and  thus  removing  it  from  the  center  so  far  as  possible,  an  attempt 
was  made  to  introduce  the  mass  into  the  machine,  spin  the  material  to 
the  sides  of  the  machine,  and  then  introduce  upon  the  interior  surface 
of  the  mass  a  weighted  screen  which  by  centrifugal  force  would  be 
pressed  upon  the  mass.  The  weight  of  the  screen  used  in  this  trial  was 
1225  grams.     The  results  of  the  trial  are  set  forth  below: 

Weighted  Screen.  No  Screen. 

Weight  of  olives 2000  grams.  2000  grams. 

Percentage  of  oil  in  olives 22.0  per  cent.  22.0  per  cent. 

Weight  of  oil  in  olives 440  grams.  440  grams. 

Weight  of  pulp  remaining 926  grams.  940  grams. 

Percentage  of  oil  in  pulp 15.8  per  cent.  16.0  per  cent. 

Weight  of  oil  in  pulp 146  grams.  150  grams. 

Percentage  of  oil  lost 33.1  per  cent.  34.2  per  cent. 

Percentage  of  oil  recovered 66.9  per  cent.  65.8  per  cent. 

The  results  obtained  from  this  trial  were  not  considered  promising 
enough  to  warrant  further  work  in  that  direction. 

Numerous  trials  were  made  with  the  small  machine  as  to  the  effect 
of  time  upon  the  yield,  but  no  effect  was  obtained  commensurate 
with  the  loss  of  time  by  extending  the  time  of  spinning  beyond  thirty 
minutes,  unless  the  mass  was  loosened  from  the  screen  and  moistened 


30  UNIVERSITY   OF   CALIFORNIA EXPERIMENT   STATION. 

with  water,  which  gave  increasing  results  up  to  about  one  hour,  which 
seemed  to  be  the  limiting  time  under  the  pressure  that  could  be  obtained 
with  the  small  machine  and  the  condition  to  which  the  pulp  could  be 
reduced. 

The  effect  of  loosening  the  mass  and  finally  washing  is  well  shown 
by  the  following  data:  The  residual  pulp  from  series  A,  B,  C,  and  D 
was  thoroughly  mixed  and  reduced  to  such  a  consistency  as  would 
allow  it  to  spread  well  in  the  machine,  and  placed  a  second  time  in  the 
centrifuge,  spun  for  thirty  minutes,  loosened  from  the  screen,  and 
mixed,  and  finally  well  washed  with  lukewarm  water. 

Weight  of  charge  used 1500  grams. 

Percentage  of  oil  in  charge   13.7  per  cent. 

Weight  of  oil  in  charge 205.5  grams. 

Weight  of  final  pulp 1217.0  grams. 

Percentage  of  oil  in  final  pulp 10.4  per  cent. 

Weight  of  oil  in  final  pulp 126.5  grams. 

Percentage  of  oil  lost  in  final  pulp 61.3  per  cent. 

Percentage  of  oil  recovered  in  second  run 38.7  per  cent. 

Thus  from  a  pulp  from  which  had  been  extracted  69.7  per  cent  of  the 
oil  in  the  original  olives  by  the  machine  without  loosening  the  mass 
from  the  screen,  and  which  carried  in  the  first  pulp  13.7  per  cent  of 
oil,  there  was  obtained  in  the  manner  indicated  above  61.3  per  cent  of 
the  oil  still  remaining,  an  increase  well  worth  the  trouble  and  .time 
expended. 

To  be  more  certain  of  the  results  obtained  with  the  small  machine 
a  larger  lot  of  olives  was  secured  and  forwarded  to  Alvarado,  where, 
through  the  courtesy  of  the  Alameda  Sugar  Company,  we  were  enabled 
to  make  a  trial  upon  one  of  the  forty-inch  centrifugals  employed  in 
their  sugar  house.  It  is  a  machine  of  this  size  which  would  be  employed 
in  practice,  and  it  was  thought  that  the  results  obtained  with  this 
machine  would  more  closely  represent  what  might  occur  in  acualt 
practice  in  working  with  this  method. 

The  only  olives  which  could  be  obtained  were  generally  of  poor 
quality  as  to  condition,  size,  and  oil  content.  They  were  far  from  such 
quality  as  would  really  indicate  the  effectiveness  of  the  work  under 
usual  conditions. 

In  the  first  run  at  Alvarado  100  pounds  of  olives  were  used  in  the 
machine,  but  when  spun  upon  the  sides  it  was  found  that  the  weight 
could  be  somewhat  increased.  These  olives  showed  on  analysis  as  fol- 
lows: Water,  36.9  per  cent;  oil,  15.0  per  cent;  total  liquid,  51.9  per 
cent. 

At  the  factory  there  was  no  convenient  way  in  which  the  oil  could  be 
collected,  and  as  the  results  could  be  as  favorably  judged  from  the  con- 
dition and  oil  content  of  the  pulp  when  the  oil  content  of  the  original 
olives  was  known,  no  attempt  was  made  to  save  the  resulting  extract. 


CALIFORNIA    OLIVE    OIL.  31 

The  pulp  was  sampled  each  fifteen  minutes  during  the  run,  and  showed 
the  following  results  for  the  several  periods. 

_.  ,  „         ,.    „  PerCent  Per  Cent 

Time  of  Sampling.  of  on  of  Water 

After  15  minutes 8.3  30.27 

After  30  minutes 8.0  25.20 

After  45  minutes 6.3  18.00 

After  60  minutes 6.1  17.50 

Or,  figured  back  to  the  original  oil  in  the  olives,  there  was  a  recovery 
after  the  end  of  one  hour  of  about  66  per  cent  of  the  oil  in  the  olive, 
which  does  not  differ  much  from  the  results  in  the  case  of  the  small 
machine. 

The  effectiveness  of  the  work  on  this  machine,  while  apparently  the 
same  as  that  with  the  smaller  machine,  must  be  looked  upon  as  some- 
what greater,  inasmuch  as  the  olives  were  in  very  poor  condition  for 
extracting  the  oil. 

It  should  be  stated  here,  however,  that  in  the  large  machine  there 
was  experienced  the  same  difficulty  as  with  the  smaller  one,  viz:  the 
separation  of  the  oil  toward  the  interior  of  the  basket  at  the  outset, 
while  the  water  was  thrown  off  through  the  screen.  While  the  oil  was 
separated  and  did  not  show  in  the  analysis  of  the  pulp,  yet  the  work 
could  not  be  said  to  be  entirely  satisfactory  from  a  working  standpoint. 

A  second  run  was  made,  using  the  same  olives,  but  washing  thor- 
oughly at  intervals  of  fifteen  minutes  for  a  period  of  one  hour.  The 
results,  however,  did  not  vary  essentially  from  those  given  above,  as  will 
be  seen  upon  an  examination  of  the  figures  set  forth  in  the  table. 

The  maximum  quantity  of  olives  which  could  be  handled  in  a  single 
machine  of  this  size  was  found  to  be  150  pounds.  Inasmuch  as  the 
large  presses  used  in  California  olive  mills  on  a  commercial  scale  will 
work  at  one  filling  3000  pounds  of  olives,  it  will  be  seen  that  the  cen- 
trifugal must  be  twenty  times  as  effective  in  time  as  the  press,  else  there 
would  be  no  gain  by  its  use  for  this  purpose.  Under  the  conditions  of 
this  work,  with  the  machine  running  at  1200  to  1500  revolutions  per 
minute,  it  required  at  least  one  hour  to  remove  the  maximum  quantity 
of  oil  from  150  pounds  of  olives;  or,  it  would  require  two  machines 
running  for  ten  hours  per  day  to  do  the  work  of  a  single  press  as  used 
in  California. 

The  results  taken  as  a  whole  and  compared  with  the  most  effective 
pressings,  and  allowance  being  made  for  the  smaller  charges  that  must 
be  used  in  the  case  of  the  centrifugal  as  against  the  large  press,  can  not 
be  considered  as  offering  much  encouragement  for  manufacturers  to 
adopt  the  former  machine  for  final  work,  although  it  might  be  used  for 
the  preliminary  treatment  in  the  removal  of  water  of  vegetation  and  a 
small  amount  of  oil. 


32  UNIVERSITY   OF   CALIFORNIA — EXPERIMENT   STATION. 

The  Use  of  the  Centrifugal  for  Demargarizing  Oil. — The  most  useful 
application  of  the  centrifugal  to  the  olive  industry  seems  to  be  its 
employment  as  a  demargarizing  filter  under  controlled  temperature 
conditions. 

There  are  certain  varieties  of  olives,  notably  the  Redding  Picholine, 
which  unfortunately  have  been  planted  to  a  considerable  extent  in 
California,  and  which  are  so  small  as  to  rank  among  the  oil  class  of 
olives.  The  oil  from  these  olives,  while  present  in  the  fruit  in  consider- 
able quantities,  carries  a  large  proportion  of  fatty  acids  which  separate 
out  at  a  comparatively  high  temperature.  While  this  is  notably  true 
of  this  variety  (Picholine),  it  is  more  or  less  true  of  certain  other  varie- 
ties; and  further,  even  in  the  same  variety,  there  seems  to  be  a  differ- 
ence in  the  relative  tendency  which  these  acids  have  to  crystallize  out, 
this  possibly  being  somewhat  dependent  upon  the  state  of  development 
of  the  fruit  and  upon  the  soil  producing  it.  Oil  made  from  these  olives, 
besides  having  a  more  greasy  taste  at  all  times,  possesses  a  compara- 
tively high  point  of  turbidity  and  congelation,  owing  to  which  it  must 
either  be  blended  with  oil  from  the  better  class  of  oil  olives,  as  the 
Mission,  thereby  reducing  the  quality  of  the  latter,  or  the  separated 
fatty  acids  must  be  removed  by  filtration  after  cooling,  else  the  oil  on 
the  shelves  of  the  dealer  assumes,  in  the  winter  months,  a  semi-solid, 
doughy  appearance,  spoiling  entirely  its  commercial  value  while  in 
that  state. 

With  the  Redding  Picholine  the  point  of  turbidity  seems  to  be  11°  to 
12°  C,  and  crystallization  begins  about  8°  to  9°  C.  As  indicated  in  the 
earlier  part  of  this  paper,  the  crystallizing  out  of  the  margarin  and 
possibly  some  other  fatty  acids  does  not  indicate  an  impure  oil,  but 
rather  the  contrary,  and  that  the  oil-making  quality  of  the  olives  is 
poor. 

For  oil  from  good  oil  olives  the  point  of  turbidity  is  4°  to  5°  C,  and 
the  point  of  congelation  2°  to  3°  C.j  but  certain  oils  have  the  point  of 
turbidity  as  low  as  3°  to  4°  C.r  and  a  congealing  point  of  0°  to  2°  C,  the 
latter  being  considered  uncongealable  in  commerce. 

Evidently  the  thing  to  be  desired,  then,  in  the  case  of  those  oils  hav- 
ing the  high  point  of  turbidity  and  congelation,  is  to  so  reduce  their 
content  of  fats  of  high  turbidity  and  congelation  point  as  to  remove 
their  tendency  to  show  these  characteristics  to  a  marked  extent  as  in 
the  varieties  named  above.  The  attempt  to  use  these  oils  in  their 
original  condition  has  forced  many  of  them  back  on  the  maker,  and  has 
had  its  influence  against  California  oils  with  some  dealers. 

To  overcome  this  trouble  an  attempt  was  made  to  treat  oils  having 
this  tendency  in  such  a  way  as  to  bring  them  within  the  range  of  tur- 
bidity and  congelation  of  the  better  class  of  oils.  This  is  done  to 
some   extent  even  now  in  this  State  by  cooling  and  filtration,  which 


CALIFORNIA    OLIVE    OIL.  33 

evidently  should  be  the  basis  of  work  in  any  scheme  for  this  purpose, 
and  in  fact  does  form  the  basis  of  a  system  used  in  Marseilles  for  a  so- 
called  complete  demargarizing  of  olive  oil.  It  would  seem  to  be  unde- 
sirable, however,  to  completely  remove  the  more  solid  fatty  acids,  as 
their  presence  to  some  extent  is  necessary  to  the  keeping  qualities  of 
the  oil,  and  if  they  be  removed  to  the  point  indicated  by  the  better 
class  of  oils  then  all  is  done  which  would  appear  to  be  essential. 

To  accomplish  the  desired  result  it  is  necessary  to  cause  the  more 
solid  fats  to  form  in  comparatively  large  crystals  by  sloiv  cooling  of  the 
oil  to  +6  or  -j-7°  C,  and  then  to  remove  the  more  fluid  oil  by  filtration. 
This  latter  work  can  be  very  quickly  and  easily  done,  and  without 
apparent  impairment  of  the  oil,  by  the  use  of  a  small  ten-inch  centri- 
fugal running  at  a  speed  of  from  2500  to  3000  revolutions  per  minute. 
,(Fig.  21.)  The  most  vital  point  in  this  work  is  slowness  of  crystalliza- 
tion, thus  securing  a  condition  which  works  well  in  the  centrifugal 
machine. 

In  the  northern  part  of  California,  at  least,  there  will  be  little  diffi- 
culty of  securing  the  correct  conditions  by  exposing  the  oil  to  the  atmos- 
pheric temperature  at  night,  which,  during  the  oil-making  season, 
seldom  fails  to  reach  a  sufficiently  low  point  to  bring  about  the  separa- 
tion of  the  solid  fats  in  the  oils  from  the  varieties  named.  There  is  no 
reason  why  the  desired  condition  can  not  be  realized,  however,  from 
the  reduction  of  the  temperature  by  any  other  means,  provided  only 
that  it  be  gradually  done. 

When  in  the  proper  condition  the  solids  spread  well  on  the  screen 
and  the  work  proceeds  rapidly.  The  material  left  in  the  machine  can 
be  used  for  fancy-soap  making,  so  that  it  is  not  an  entire  loss. 

By  this  treatment  it  is  possible  to  obtain  from  the  class  of  oils  under 
discussion  an  oil  which  will  resist  a  temperature  of  +1°  C.  to  +3°  C, 
and  will  possess  none  of  the  greasy  characteristics  which  were  in  the 
original  oil.  In  the  operation  the  oil  will  lose  about  10  per  cent  of  its 
weight  when  working  under  the  conditions  indicated,  on  account  of  the 
separated  margarin,  but  the  quality  of  the  resulting  oil  will  be  appre- 
ciably higher  and  will  bring  a  better  price. 

In  this  work,  as  with  all  in  connection  with  the  preparation  of  olive 
oil,  absolute  cleanliness  is  the  price  of  good  oil.  It  is  also  best  that  the 
portion  of  the  apparatus  which  comes  into  contact  with  the  oil  should 
be  tinned,  so  that  it  may  not  impart  a  foreign  taste  to  the  oil. 


REPORTS  AND  BULLETINS  AVAILABLE  FOR   DISTRIBUTION. 


REPORTS. 

1896.  Report  of  the  Viticultural  Work  during  the  seasons  1887-93,  with  data  regarding 

the  Vintages  of  1894-95. 

1897.  Resistant  Vines,  their  Selection,  Adaptation,  and  Grafting.    Appendix  to  Viti- 

cultural Report  for  1896. 

1898.  Partial  Report  of  Work  of  Agricultural  Experiment  Station  for  the  years  1895-96 

and  1896-97. 
1900.    Report  of  the  Agricultural  Experiment  Station  for  the  year  1897-98. 
1902.     Report  of  the  Agricultural  Experiment  Station  for  1898-1901. 

BULLETINS. 

No.  121.  The  Conservation  of  Soil  Moisture  and  Economy  in  the  Use  of  Irrigation  Water. 

125.  Australian  Saltbush. 

127.  Bench-Grafting  Resistant  Vines. 

128.  Nature,  Value,  and  Utilization  of  Alkali  Lands. 

129.  Report  of  the  Condition  of  Olive  Culture  in  California. 

131.  The  Phylloxera  of  the  Vine. 

132.  Feeding  of  Farm  Animals. 

133.  Tolerance  of  Alkali  by  Various  Cultures. 

134.  Report  of  Condition  of  Vineyards  in  Portions  of  Santa  Clara  Valley. 

135.  The  Potato-Worm  in  California. 

136.  Erinose  of  the  Vine. 

137.  Pickling  Ripe  and  Green  Olives. 

138.  Citrus  Fruit  Culture. 

139.  Orange  and  Lemon  Rot. 

140.  Lands  of  the  Colorado  Delta  in  Salton  Basin,  and  Supplement. 

141.  Deciduous  Fruits  at  Paso  Robles. 

142.  Grasshoppers  in  California. 

143.  California  Peach-Tree  Borer. 

144.  The  Peach-Worm. 

145.  The  Red  Spider  of  Citrus  Trees. 

146.  New  Methods  of  Grafting  and  Budding  Vines. 

147.  Culture  Work  of  the  Substations. 

148.  Resistant  Vines  and  their  Hybrids. 

149.  California  Sugar  Industry. 

150.  The  Value  of  Oak  Leaves  for  Forage. 

151.  Arsenical  Insecticides. 

152.  Fumigation  Dosage. 

153.  Spraying  with  Distillates. 

154.  Sulfur  Sprays  for  Red  Spider. 

155.  Directions  for  Spraying  for  the  Codling-Moth. 

156.  Fowl  Cholera. 

157.  Commercial  Fertilizers. 

CIRCULARS. 

No.  1.    Texas  Fever.  No.  8.  Laboratory    Method    of    Water 

2.  Blackleg.  Analysis. 

3.  Hog  Cholera.  9.  Asparagus  Rust. 

4.  Anthrax.  10.  Reading   Course    in    Economic 

5.  Contagious  Abortion  in  Cows.  Entomology. 

6.  Methods  of  Physical  and  Chem-  11.  Fumigation  Practice. 

ical  Soil  Analysis.  12.  Silk  Culture. 
7      Remedies  for  Insects. 

Copies  may  be  had  by  application  to  the  Director  of  the  Experiment 
Station,  Berkeley,  California. 


